The invention relates to a data processing system with a first and a second system unit, which can be separated from one another. The invention further relates to a method for separating two system units of a data processing system.
From the state of the art it is known to provide a system unit of a data processing system with an energy store, e.g. a battery or a condenser, for buffering the power supply. For example, the energy store can serve for buffering for a short time if the mains supply fails.
For portable computers, batteries are generally used as energy stores, particularly for so-called notebook PCs, e.g. IBM THINKPAD Notebook. It is also possible to operate a portable computer in combination with an additional system unit in a static operation. The additional system unit is then generally a so-called docking station, e.g. IBM Dock II (cf. IBM ThinkPad Dock II, User Manual, IBM Part Number 13H1664 (84G9682)).
A Docking Station offers extended functions, so that by combining a portable computer with the docking station the functionality of the data processing system thus formed overall corresponds to the functionality of a stationary desk top computer system. It is particularly advantageous if the docking station permits so-called hot-docking and hot-undocking. Then the portable computer can be connected with and disconnected from the docking station during operation. It is then not necessary to switch off the portable computer when connecting and separating the system units and to restart the operating system again after connection. In particular the IBM Dock II docking station permits the hot-docking and hot-undocking of an IBM ThinkPad.
A docking station of the type mentioned is also known from U.S. Pat. No. 5,265,238. A power supply system for a portable computer with a charge sensor is known from U.S. Pat. No. 5,345,392.
Known docking stations are designed for stationary operation on the mains. For many applications, however, it is advantageous if not only the notebook PC but also the complete system of notebook PC and docking station is capable of operation independent of the mains.